[win32] Widget constructor calls overrideable public method; breaks EGit's `FindToolbar`

[tomaswolf]

Describe the bug
The Widget constructor

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Widget.java

Lines 179 to 197 in a9598b8

	public Widget (Widget parent, int style) {
	checkSubclass ();
	checkParent (parent);
	this.style = style;
	this.nativeZoom = parent != null ? parent.nativeZoom : DPIUtil.getNativeDeviceZoom();
	display = parent.display;
	reskinWidget ();
	notifyCreationTracker();
	registerDPIChangeListener();
	}
	void registerDPIChangeListener() {
	if (display.isRescalingAtRuntime()) {
	this.addListener(SWT.ZoomChanged, event -> {
	float scalingFactor = 1f * DPIUtil.getZoomForAutoscaleProperty(event.detail) / DPIUtil.getZoomForAutoscaleProperty(nativeZoom);
	handleDPIChange(event, scalingFactor);
	});
	}
	}

calls via registerDPIChangeListener the public and overrideable method addListener. If that method is overridden in a subclass it will run before the subclass instance is initialized. This is bad practice, and in fact it breaks EGit's FindToolbar: see eclipse-egit/egit#117 .

Possible fix

Replace the call to this.addListener at

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Widget.java

Line 192 in a9598b8

this.addListener(SWT.ZoomChanged, event -> {

by this._addListener (with underscore, package-private).

[fedejeanne]

Makes sense. Would you like to provide a PR?

[fedejeanne]

FTR I see other calls in the code that may run into the same issue, constructors being the the most prominent ones:

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There might be many more, I didn't look extensively

[tomaswolf]

Would you like to provide a PR?

Sorry, no. I don't have a Windows development machine, and I'm not set up for SWT development.